Lapping machine



vJuly 11, 1939.

W. H. WOOD July 1l, 1939.

w. H. wQoD 2,166,085

LAPPING MACHINE Filed Nov. 3, 1938 5 sheets-sheet 2 'f July 11, 1939. w. H. woon 2,166,085

LAPPING MACHINE v Filed Nov. 3, 195s 5 sheets-sheet s -Wt 260 H @la WALLACE H. WDUJJv n @WM-WQ L0 Sham Patented July I11, 1939 LAPPING MACHINE Wallace H. Wood, Worcester, Mass., assigner to Norton ComPMLY, Worcester, Mass., a corporation of Massachusetts Application November 3,

a claims.

This invention relates to abrading machines, and more particularly to a lapping machine for lapping crankshafts and the like.

One object of the invention is to provide a simple and thoroughly practical lapping machine for simultaneously lapping or polishing a. plurality of crankpins and main bearings on a crankshaft or the cams and main bearings on a camshaft. A further object of the invention is to' provide a lapping machine in which all of the crankpins and main bearings may be simultaneously lapped. A further object lof the invention is to provide a crankshaft lapping machine for simultaneously lapping the crankpins and bearings oi a.cranksl1aft, in which a plurality of lapping arms are hydraulically operated.

Another object of the invention is to provide a lapping machine for lapping work pieces such as crankshafts, camshafts and the like, in which the footstock, the lapping arms, the lapping arm clamping mechanism, the lapping arm carrier, and the footstock are all hydraulically operated by independent uid motors. A further object of the invention is to provide such a lapping machine in which a common control valve controls the admission of fluid to the footstock cylinder,

. the lapping arm' cylinders, the lapping arm clamping cylinder, and the lapping arm carrier cylinder.

A further object of the invention is to provide a hydraulically operated lapping machine in which all of the hydraulically operated mechanisms are interlocked by the control valve and a plurality of automatically actuated latches or stops are provided so as definitely to interlock the various mechanisms of' the'machine. Another objectuof the invention' is to provide an .electrical interlock between the main control lever, lie footstocls actuating mechanism, and theA lap arm clamping mechanism so that-. the headstock cannot be set in` motion until thev footstock center has moved into operative supporting engagement with( thev work piece to be lapped and the clamping mechanism has released the lapping arms. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as willbe exemplilied in the structure to be hereinafter described, y and the' scope of the application of. which 'will be indicated in the following claims.

A the accompanying drawings in which is 193s, serialNo. 233,625

(ci. 51- 1s) l,

shown one of various possible embodiments of the mechanical features of this invention,

Fig. l is a. front elevation of the improvedcrankshaft lappingmachine; v

Fig. 2 is an end elevation, on an enlarged scale, -of the improved crankshaft lapping machine;

Fig. 3 is a diagrammatic illustration of the `hydraulic actuating mechanism and piping together with the control valve andthe interlocking stop or latchjmechanism therefor;

Fig. 4 is a horizontal sectional view through the hydraulic control valve, showing the valve in its second position during its rearward move- -`ment;

Eig. 5 is a vertical sectional View through the control valvel showing the valve in its third position on its rearward movement;

Fig. 6 is a similar vertical sectional view, `showing the control v'alve inits rearward or righthand position;

Fig. '7 is a similar vertical sectional View, showing the control valve in its second position dur-v ing its forward movement;

Fig. 8 is a similar horizontal seconnal view,

showing the control valve in its third position\ during its forwardmovement;

Fig. 9 is a fragmentary sectional View showing the rear end of the control valve and latch mechanism in elevation;

Fig. 10 is a right-hand end elevation'of the headstock mechanism, on an enlarged scale;

11 is a fragmentary sectional view taken approximately on the line I I-ll of Fig. '2, showing the lapping arm clamping mechanism;

Fig. 12 is a fragmentary end elevation fof a n crank lapping arm and its supporting and clamping mechanism; and v l Fig. 13 is a fragmentary cross-sectional view,

on an enlarged scale, taken approximately on y the line |3-l3 of Fig. 11.

A. crankshaft lapping machine has been illustrated in the drawings comprising a base 20 which supports a longitudinally reciprocable work supporting table 2|. Table ways are provided between the base`2ll and the table 2l -which in the preferred form are of an antifriction type. The base V2|) is provided with a plate 26 which is 'fixed to the 'base 20 and is provided at its edge portions with grooves 21 and 28 which serve as inner raceways for a pair of spaced rows of anti-friction balls 29 and 30.A respectively. A cage is provided between the races to :space the .balls 29 and 30 longitudinally, as desired. This the lapping operation. y

Headstock The headstcck 22 is provided with a rotatable spindle 33 which is supported in bearings (not shown). 'Ihe headstock spindle 33 may be rotated. from any suitable source of power, such as an overhead belt drive, or a self-contained electric motor. In the preferred construction, an

` tially identical with that shown in the prior United States Patent- No'. 2,092,734 dated September 7, 1937, except that it does not require the built-in cycle counting mechanism. Reference may be had to the above-mentioned patent for details of disclosure not found herein.

Table reciprocation Y In the lapping of crankpins and main bearings of an automotive crankshaft or the cams and main bearings of an automotive camshaft, it is desirable to provide a relative reciprocatory movement between the crankshaft or camshaft being lapped and the lapping or abrading element'to prevent production of abrasive grain markings on the pins and bearings of the crankshaft. In the present case, the work table 2| is arranged for a longitudinal reciprocatory movement which is preferably accompished by a translation of the rotary motion of the headstock spindle 33 into a'reciprocatory movement of the table 2|. The specic mechanism for reciprocating the tablev 2| has not been illustrated in the present case, since this'mechanism is identical with that shown in the prior United States Patent No. 2,092,734 dated September 7, 1937, to which reference may be had for details of the table reciprocating mechanism not found herein.

Footstoek The other end of the crankshaft 2l is supported by the footstock. 23 which is provided with v a footstock center 5I. The center 5| is carried ed for'movingthe footstock center 5| rapidly to and froml an operative position to support one end of a crankshaft 24 within the machine. This mechanism comprises a fluid pressure cylinder 58 having a s'lidably mounted piston 59 contained therein. The piston59 is connected to one end 'lli of a piston rod 60 which is connected to a pin 6|. The'central portion of the pin 8| is slabbed off on opposite sides so as to slide within an elongated slot- 62 formed in thelower enlarged end of the piston rod 50. The pin il serves as a central'pivotal connection' between a pair of toggle levers 63 and 84.. The toggle lever 84 is connected to the footstock frame by means of a stud 55. The other end of the toggle lever 63 is connected by a stud 68 with a slidably mounted hollow sleeve 81 which slides within an aperture 68 within the sleeve 55. The sleeve 61 footstock 23 may be readily reciprocated during is held against rotation by means 'of a pin 89 which is carried by the sleeve 55 and rides within an elongated slot in the sleeve 5.5. A spring 18 is contained within the sleeve 61 and is inter` posed between the end of an aperture of the sleeve 81 and a thrust collar 1|.

When fluid under pressure is admitted through a pipe 12 to a cylinder chamber 13, the piston 59 is moved downwardly and the toggle levers 63 and 64 are moved from the dotted line positions 63a and 64a into the full line positions 63 and 6l (Fig. 3) which serves to move the sleeve 61 into the position illustrated. This movement serves to compress the spring 10 and, through the connecting parts. moves the sleeve 55 and footstock center 5| into operative supporting engagement with the end of the crankshaft 24.l During this movement, uid is exhausted from a cylinder chamber 14 through a pipe 15. The admission to and exhaust of fluid from the footstook operating cylinder 58 will be hereinafter described. This footstock is identical with that shown in the prior United States Patent No. 2,117,960 dated May 17, 1938, .to which reference may be had for details of disclosure not contained herein.

. Lappz'ng arm support It is desirable to provide a movable support for a plurality of lapping arms so that they may be simultaneously and. quickly moved into an operating'or an inoperative position as desired. A pair of spaced arms 89, only one of which has been illustrated in the drawings (Fig. 2), are mounted on a rock shaft 8| which is supported in bearings on the rear of the machine base 20. The arms 80 are provided with horizontally extending portions which are connected by two spaced bars 82 and 83 which serve as slide bars or ways for supporting a plurality of lapping arms to be hereinafter described.

The lapping arm assembly supported by ythe arms 80 is arranged so that it may be automatically moved to and from an operating position to facilitatel loadingy of crankshafts into the machine and removing them therefrom after a lapping operation has been completed. In order to move the entire lapping arm assembly to an inoperative position, a fluid pressure mechanism is provided including a iiuid pressure cylinder 84 which is pivotally connected by means of a stud 85 within the base 20 of the machine. A piston 86 is slidably mounted within the cylinder 84 and is connected to one end of a piston rod 81. The other end of the piston rod-81 is connected by a stud 88 with an arm 89 pivotally mounted on a shaft 90 supported within the base 20. The other end of the arm 89 is connected by a stud 9| to one end of a link 92. ,The other end of the link 92 is connected by a stud with. a toggle lever 94. The adjacent ends of the toggle lever 94 and a toggle 95 are connected by a stud 93.

The toggle lever 94 is connected at its other end 'shaft 8| and is arranged to rock the shaft 8| together with the arm 80 andl all of the crankpin and bearing lapping arms together with their.

supporting and actuating mechanisms either into or away from an operating position.

'I'he levers 89, 92, 94 and 95, as shown in full' lines in Fig. 2, are iii-a position to hold the arm 98 and the arms 80 together with the entire lapping arm assembly in an operating position. Af-

Y ter a lapping operation has been completed, fluid under pressurevisadmitted to the cylinder 84 to cause the piston 85 and piston rod 81 to move toward the right (Fig. 2) to shift the levers 89, 92, 94 and 95 and arm 98 into the dotted line positions 89a, 92a, 94a, 95a and 98a. This movement serves to rock the arms in a clockwise direction (Fig. 2) to move the entire lapping arm assembly to an inoperative position.

Fluid pressure system A fluid pressure system is provided to control the admission of huid under pressure to the cylinder 84. A pump 99 Within the base 20 of the machine draws iiuid through a pipe |00 from a reservoir |0|' within the base 20 and passes uid under pressure through a, pipe |02 to a reverse or control valve |03. The valve |03 is of a piston type having a valve stem |04 which is provided at its outer end with a manually operable actuating knob |05.

A plurality of valve pistons ||0, |l|, ||2 and H3 are formed integral with the valve stern |04. Fluid under pressure passing through the pipe |02 passes into-a valve chamber ||4 located between the valve pistons and ||2 and passes out through a pipe H5 into a cylinder chamber H6 Within the cylinder 84 to cause the piston 86 to move toward the left (Figs. 2 and 3) to shift the lapping arm support arms 80 in a counterclockwise direction (Fig. 2) to position the crank-- pin and bearing lapping arms in an operating position.

During the admission of iiuid under pressure to the cylinder chamber H6, fluid is exhausted from a cylinder chamber at the other end of the cylinder 84, through a pipe IIB, through a valve chamber ||9 located between the valve pistons ||2 and ||3, and out through a pipe |20 into the reservoir |0|. valve |2| is 'connected by a pipe |22 with the pressure pipe |02 and serves to by-pass excess uid under pressure within the pipe |02 to the reser Voir |0|.

The controlvalve |03 also serves to control the admission of fluid to the footstock actuating cylinder 58. The pipe 12 is connected to the pipe' ||5 and serves to convey fluid under pressure to the footst'ock cylinder chamber 13 simultaneously with the passage of iiuid under pressure to the cylinder chamber |||i in the cylinder 84. vThe pipe -15A connects the cylinder chamber 14 of the cylinder 58 with the pipe ||8 so that in the position of the control valve |03 (Fig. 3), fluid willexhaust simultaneously from the cylinder chamber 14 in the cylinder 58 and from cylinderchamber |I1l in the cylinder 84.

'When the control valve |03 is shifted into the position illustrated in Fig. 3, fluid under pressure simultaneously enters.both cylinder 58 and the cylinderV 84 and due to the fact that 'less power is required to move the footstock than the lapping varm assembly, the footstock center moves first intoan operative position, after which the lapping arm assembly moves to an operative position adjacent to the crankpins and bearings tobe Main control valve.

The controlvalve |03 is preferably moved in both directions by fluid under pressure which is preferably controlled by a main control valve |23. The main control valve |23 is preferably of a rotary type which is actuated by means of a lever |24 i-lxedly attached to the valve rotor; Fluid under pressure from-the pump 99 passes through .a pipe |25 to the main control valve |23 and in A fluid pressure relief away from an operative the position illustrated in Fig. 3 passes through a pipe |26 into a valve chamber |21 located in the right-hand end of the control valve |03 so as to shift the valve stem |04 'and the pistons formed integrally therewith toward the left :.(Fig. 3). During this movement of the valve stem |04 toward the left, fluid within an end chamber |28 the valve stem |04 toward the right or toward the left is restricted by. a series of stop plungers to be.

hereinafter described.

A spring |3| interposed between the lever |24 and a stud ixed on the base of the machine normally tends to hold the lever |24 in position |24a so that the valve is normally held in its rearward position with the parts of the machine positioned for a loading operation.

Lappin'g arms In order that all of the crankpins and main bearings on the crankshaft 24 may be simultaneously lapped, a plurality of crankpin and bearing Vlapping arms are provided which correspond in The main bearing and crankpin lapping arms' are supported in spaced relationshipl with each other so as to simultaneously engage and lap the three main bearings and the four crankpins on the crankshaft 24. The bearing lapping arms and crankpin lapping arms are substantially identical in construction.- The vbearing lapping arms are stationary `while lapping the main bearing surfaces which are concentric with the axis of rotation of the crankshaft 24, whereas the crankpin lapping arms are rocked during the lapping operation dueto the fact that they engage a crankpin which revolves about the axis of rotation of the crankshaft 24.

A side elevation of the lapping arm |35 is shown in Figs. 2 and 12. The lapping arm |35 as wellv as all ofthe other lapping arms are each provided with a pair of pivotally mounted lap supporting arms |40 and |4| which are provided at their operative ends with partially cylindrical lap supporting blocks |42 and |43, respectively. The arms |40 and |4| are pivotally supported by the studs |44 and |45 onthelapping arm |35. The other ends of the arms |40 and |4| are interconnected by means of a pair of toggle levers |46 and |41 which are connected together at their `inner ends by means'of a stud |48. The stud |48 the lap supporting members |42 and |43 are maintained in operative engagement to hold an abraa portion of the crankshaft 24.

The lapping supporting arms |40 and |4| are arranged to be automatically moved into and position, and in the preferred construction a hydraulically operated mechanism is provided for actuating the sameA Icomprising a uid pressure cylinder |35a formed sive or lapping element in operative contact with integral with theupper end of the lapping arm |35. A piston |351) is slidably mounted therein' and is connected toone end of a piston rod |35c. The other end of the piston rod |35cl is connected by a stud |50 with a link |5|. The other end of the link |5| is connected to the stud |48 which pivotaily connects the adjacent ends of the toggle levers |46 and |41. -It will be readily apparent from the foregoing disclosure that when the piston |b is moved downwardly, that is, toward the left (Fig. 2) the piston rod |350 and the connecting link |5|wll1 be moved also in a downward direction toward the left which serves to unlock the toggle levers |46 and |41 and thereby to rock the lap 'supporting arms |40 and |4| together' withthe lap supporting elements |42 and |43 to an inoperative position out of engagement with the crankshaft 24. When uid under pressure is passed through a flexible pipe |35d into a cylinder chamber |358, the piston |356. will be movedupwardly to move the toggle levers |46 and |41 into a straight-line position (Figs. 2 and-12) to move the abrasive lapping element into an operative position in engagement with the work piece 24 for a lapping operation. Similarly, when iiuidunder pressure is admitted through. a exible pipe |35f to cause a downward movement of the piston |35b toward the left (Figs. 2, 3 and 12), the toggle vlevers and 41 will be unlocked to move the lap-l ping elements to an inoperative position.

Itis to be noted in the drawings (Fig. 3) that I each ofthe lapping arms is provided with an independent iiuid operated piston and cylinder as well as piston rods which have been designated in the diagram with the same reference numerals as thelapping arm on which it is mounted, the cylinders being designated by the letter a, the pistons by the letter b,'the piston rods by the letter c, and cylinder chambers by the letter e.

y Itis desirable that all of the lapping elements represented by the supporting members |42 and |43 (Fig. 2) be moved into and away from an operating position simultaneously. This is preferably accomplished by providinga pair of longitudinally extending pipes or manifolds |53 and |54 'which are'xedly supported on the spaced arms and serve as a common source of iluid underv pressure which may be forced either through the ilexible pipe |35d to move the lapping element into an operative position, or when the fluid under pressure is reversed. to now through the exibe pipe 35f -simultaneously to move all of the lapping elements to an inoperative position after the lapping operation has been completed. 'The admission to and exhaust of iluld from the manifolds or pipes |53 and |54 is lcontrolledby the control valve |03. A pipe |55 is connected between the manifold or pipe |53 and the valve chamber I|4 and serves in the position oi thevalve |03 (Fig. 3) to admit uid under pressureto the manifold or pipe |53, into the.

cylinder chamber |35e, and simultaneously to all of the other corresponding cylinder chambers port for the lapping arms being identical, only one support has been illustrated in detail. An arm |65 is pivotally mounted on a supporting member |86 which is clamped in adjusted position on the guide rods 82 and 83. The lower end of Athe arm |65 is pivotallyconnected to the connection |61. A pivotal connection |68 serves to connect the arm |65 with the lapping arm |35 so that the arm |35 is free to move. Allof the lapping arms, both crankpin and main bearing `isupporting member |66 by means of a pivotal arms, are mounted in the same manner so that when-the lapping elements are clamped in lapping engagement wi-th a. crankpin and main bearing, the crank lapping arms may follow, as the crankpin is revolved to'produce the desired lapping action.

A ilexible abrasive paper or cloth ispreferably utilized as an abrading or lapping medium. Each of the lapping arms is provided with a separate strip of continuous Aabrasive paper which wraps around the crankpin ormain bearing and is held in position thereagainst by the lap supporting members |42 and |43. A rod |10 isfsupported on the rear of each of the supporting members |66 by means of a bracket |1| and serves as a-supis wound up on a reel |18 which is supported by i a stud |19 carried by a bracket |80 supported o n the lap supporting arm |40.

The lap supporting members |42 and 43 are mounted so that they may float or move relative to the arms |40 and |4|, so that the lap supporting members |42 and |43 are self-aligning when brought into .operative engagement to support the labrasive paper on a crankpin or main bearing for a lapping operation. The brackets |11 and |80-are ixedly mounted to the iioating lap supporting members |42 and 43. A holding pawl |8| cooperating with a ratchetv wheel on the end of the reel |18 servesl to prevent unreeling of the worn abrasive paper wound up on the reel |18 when the lap supporting arms are moved to and I from an operating position. As illustrated in the drawings, the abrasive paper is fed manually when f desired by the operator by manually turning the reel |18.y Only one of the reels |18 and the associated parts to guide the abrasive paperl through. to the reel |18 have been illustrated in detail. Each lapping arm is providedV with similar equipment supported on a separate supporting member |66. The abrasivev paper -and windup reels for each of the lapping arms are illustrated in the front elevation of the machine, as shown in Fig. l.

The lapping arm |33 is supplied with a strip of abrasive paper which is wound up on a reel |86. 'I'he lapping arm |36' is provided with a strip of abrasive paper |81 and the used portion thereof is wound upon a reel |88. The lapping arm |31 is supplied with a stripv of abrasive paper |89, the 'used portion of which is wound up on a reel |90. The lapping arm |34 is supplied with a strip of abrasive paper |9|', the used portion of which is wound up on a reel |92. The arm M38 is supplied witha strip of abrasive paper |83, the used portion of which-is wound up on' a reel |94. The lapping arm |39 is supplied with all of the lapping 'arms in their indexed position relative to the supports |66 before the lap supporting members |42 and |43 are released from operative position and the lapping arm assembly swung to an inoperative position to facilitate loading of-the machine. It is desirable to provide such a clamping device so that when the arms 80 are moved to an operating positionv after a new crankshaft' has been loaded into the machine, all of the lapping arms Will be in the proper indexed position so that the lap supporting members |42 and |43 may be automatically brought into engagement simultaneously with the crankpins and bearings .of the crankshaft 24.

In order that the lapping elements may be guided in their swinging movement and 4held against lateral movement during the reciproca.-A

tion or oscillation of the crankshaft 24 during the lapping operation, a pair of parallel guiding plates 200 and 20| are xedly mounted on the supporting bracket |86 and are spaced apart by a distance equal to the thickness of the lapping arm |35. The lapping arm |35 is guided thereby and is held against lateral movement by the guiding plates 200 and 20|. The lapping arm |33 is similarly guided by the guiding plates 202 and 203. The-lapping arm |36 is guided by guiding plates 204 and 205. The lapping arm |31 is guided 'by guiding plates 206 yand 20?. The lapping arm |34 is guided by guide plates 208 and 209. The lapping arm |38 is guided by guide plates 2|0 and 2H, and the lapping arm |33 is guided by guide plates 2 2 and 2|3.

Lap arm-clamp device In order toA provide means for simultaneously clamping all of the crankpin and bearing lapping arms in their respective index positions, the guide plates200, 202, 204, 206, 208, 2|0 and 2|2 are each provided ,with a groove orguideway 2|4 which guide plate 200 is provided with a pair of cams 2| 1 and 2|8 which engage the cam shaped depressions 2|6 formed in 'the slidably mounted member .2|5.' It will be readily apparent that if the slide 2|5 is moved upwardly (Fig. 11) vrelative to the guiding plate 200, the cam depressions 2|6 engaging the fixed cams 2|'| and 2|8 will cause the slide member 2|5 to move toward the right (Fig. I1) and therebybind or clamp the lapping arm |35 in a viixed position relative to the guide plates 200 and 20|. Each of the lapping arms |33 to |39 inclusive is provided with an identical clamping means, consequently only one of these clamps has been illustrated indetail. The guide plates` 202, 204, 206, 208, 2|0 and 2|2 are eachprovided with a clamping slide 202a, 20ML, 20611 208a, 2|0a and 2|2a, respectively. l

In order simultaneously to clamp all of the lapping arms, a mechanism is provided for simultaneously actuating the clamping slides 2 I5, 202a,

204a, 20Go, 20341, `2|0'a and 2|2a. As illustrated in I position. 1

the drawing a shaft 22| is rotatably supported inaperturesin the guiding plates 2 00 to 2|2 inclusive. Each of the clamping slides is provided 22| carries an eccentric 223 which rides within the elongated slot 222. When the shaft 22| is rotated, the eccentric 223 rotating within the elongated slot 222 causes the clamping slide 2|5 to move relative to the guiding plates 200 and 20 i.

The shaft 22| is provided with a plurality of -with an elongated slot 222 (Fig. 13). The shafteccentric members corresponding to the eccentric 223, each of which is arranged to engage elongated slots in the respective clamping slides 202e,-

200', goed, 2080, zla and Zigiz.

Clamp `actuating motor A vane type uid' pressure motor 230 is provided for rocking the shaft 22| to clamp and release the lapping arms. The motor 230 is provided with a rotor shaft 23| which supports a rotary vane 232. Tle rotor shaft 23| projects from the motor casing toward the left (Fig. 1l). An arm 233 is supported on one end of the rotor shaft 23|. The arm233 is provided with an enlarged head 234 having a notch 235 formed inthe outer end thereof. A lever 236 is xedly mounted on the shaft 22E and is provided with a spring-pressed plunger 231 which is arranged to engage the notch. 235 to lock the lever 236 tothe lever 232 so that .the rotation of the vane 232 of the motor 230" will be transmitted to rotate the shaft 22| to clamp or release the lappingarms. v"ihe plunger 231| is connected with a knob 238 by means of which the plunger 237 may be withdrawn from the notch 235 so that the clamping mechanism may be 'opy the control lever |23 is moved in a counterclockwise direction (Fig. 3) to shift the valve i 23 soy as to admit fluid under pressure through the pipe 23 into the vaive chamber i2? to shift the control valve l 33 and start the cycle of operation.

it is desirable that the various 1 mechanisms' should operate in the following sequence:

(a) Footstock center 0| moves in to grip the work. f

(b) Arms 90 which support the crankpin. and' bearing lapping armsswing' forward into an operating position.`

(c) Jaws close ontoiwork. (d) Lappingarms unclamped. (e) Headstock startsrotation, allowing work to rotate a predetermined number of rotations..

(f) Headstock stops rotation... (g) Lapping arms are clamped in an indexed (h)` Jaws open. v (i) Arms swing back to inoperative position. (i) Footstock center 5| moves out of engagement with work to release the same, after which the crankshaft chine.

Interloclcs.

Theports in the valveY |03 are so arranged that fluid under pressure will be admitted to the varimay be unloaded from the ,ma--4 ous hydraulic cylinders in the sequence above enumerated. It is, however, desirable that the various mechanisms have suiiicient time to function before the next mechanism operates. It is,

the various mechanisms which may comprise a series of' stops which serve to limit the movement of the control valve when it is moved in either direction. These stops are interconnected with the various mechanisms so that after a mechanism has performed its function, the valve stop will be automatically withdrawn, thereby permitting a further movement ofthe control valve |03. A

A stop collar 248 is fixedly mounted on th rear end of the valve stem |04. The collar 248 is arranged to slide within an aperture within a 'casing 249, flxedly mounted on the rear end of the casing of the valve |03. The casing 249 serves as a support for a plurality of spring-pressed` stops which are arranged intermittently to stop the movement of the valve stem |04 when it isy moved either towards the rear after a lapping op" eration has been completed or when the valve is moved forward after a. new crankshaft has been loaded into the machine to start a lapping operavtion. As shown in Fig. 3, the valve |03 together with the other mechanisms of the `machine are of a clutch operating shaft 255 jon the headstock 22 whichis connected to move a clutch 256 into or out of engagement to start the headstock rotation. As shown in the drawings (Figs. 3 and 10), the headstock clutch is engagedand the crank- Shaft is being lapped. This. lapping operation continues until a solenoid controlled by an elec-l trical time delay ,relay to be hereinafter described disengages the headstock .clutch and automatically stops the heads'tock after the lapping operation has continued for a predetermined time interval. When the clutch 256 is disengaged to stop the headstock rotation, the shaft 255 and bell crank 254 are rocked in a clockwise direction and this movement serves to pull on the exible cable 253 to rock the bell crank 252 in a counterclockwise direction and thereby automatically withdraw the stop plunger 250 from the path of the stop collar 248. During the lapping operation when the headstock isrunning, the stop plunger 250 prevents accidental shifting of the valve towards the rear and holds it locked ina forward operating position'.

The valve stem |04 may-then be shifted until thevstop collar 248 engages a stop plunger 260 wire or flexible cable 263v is wound partially whichis arranged in a manner to be hereinafter described to prevent further rearward movement lof the valve until the lapping arms are clamped in position. The spring-pressed stop plunger 260 is connected by a link 26| with one arm of a bell crank lever 262, the other arm of which is connected to a flexible cable or Bowden wire 263. A spring 264 normally tends to move .the bell crank in a clockwise direction. The Bowden around the periphery of a disk 2,66 which is mounted on the end ofthe shaft .22| and is conheated by ,means of ascrew 265 with lthe periph. eryof the disk'266 (Fig. l1). The valve stem |04 cannot hemoved further towards its rearward 'position' untlil fluid.: under pressure admitted 22| and the disk 266 also in a clockwise direction which serves to pull the flexible cable or Bowden wire 263 toward the left (Fig. 3), thus rocking the bell crank lever 262 in a counterclockwise direction which serves automatically to withdraw the stop plunger 260 out of the path of the stop collar 248.

The valve stem |04 may then be moved rearwardly until it is again stopped by the stop collar 248 engaging the stop plunger 210. The plunger-210 is connectedy by a link chain 21|- with one arm of abell-crank lever 212, the other arm of which is connected to a 'flexible cable or Bowden wire 213. The other end of the Bowden wire or'cable 213 is connected to the stud |48'which connects the toggle levers |46 and |41 with the hydraulic actuating mechanism. The valve stem |04 cannot be moved further to the rear .until fluid under pressure admitted through the pipe |56 into the manifold or pipe |54 causes a downward movement of all of the pistons |331), |3611, 131i), |341), |38b, |391) and |351 to actuate the toggle levers and open the lap supporting arms or jaws. The downward movement of al1 of these pistons serves through the Bowden wire 213 to rock the bell crank lever 212 in a clockwise direction (Fig. 3) which in turn, through the link chain 21|,`automatica1ly withdraws the .l

stop'plunger 210 from the path of the stop collar 248. After the plunger 210 has been withdrawn from th'e path of the stop collar 248, the valve stem |04 is` shifted automatically into its extreme rearward position, namely, that shown in Fig. 6, so as to admit fluid under pressure through the pipe 8 into the cylinder .fchamber ||1 of the cylinder 84 to rock the arms 80 so as, to simultaneously withdraw the entire lapping arm assembly to an inoperative position.

At the same time the arms so withdraw nie mppmg arm assembly to an inoperative position, uid

under pressure is admitted through the pipe 15- be removed from the machine.

After a new shaft has been inserted in the machine, the valve stem |04 is moved toward the left (Fig. 7). The valve stem |04 can be moved until the stop collar 248 engages a stop plunger 280 which prevents further forward movement of the valve. This forward movement of the valve is sufficient to uncover theport and admit fluid under pressure through the pipe ||5 into the cylinder chamber ||6 of .the cylinder 84 to cause the arms supporting the lapping arm assembly to move to an operating position. The stop plunger 280 .is connected by a link chain k28| with a'bracket 232 which is xed t0 the lever 95. When the lever is moved into the position illustrated in Fig. 2, the stop/plunger 280 is moved downwardly (Fig. 3), thus permitting` a further automatic forward movement of to uncover a -port so as to admit fluid' under pres- 25 sure through the pipe |55 to manifold or pipe |53 and thereby admit duid under pressure to the lapping arm cylinders to close the lap supporting arms or jaws into operating engagement with the work. This closing movement causes the pin |48 to move upwardly (Fig. 3) into the position illustrated therein which serves through the Bowden wire 213 to rock the bell crank lever 302 in a connterclockwise direction automatically to withdraw the stop'plunger 300 out of the path of the stopfcollar 248, thus permitting' the valve stem automatically to be moved further in a forward direction, that is, toward the left (Fig. 3) until it uncovers a port to admit iluidl under pressure through the pipe 4305 to actuate the lapping arm clamping motor '230 to l' unclamp the' lapping arms. This movement rotates the shaft/22| Yand the disk 265 in a counterclockwlsedirection which serves through a Bowden wire or flexible cable 3|0 to rock a lever 3|| which is pivotally mounted on a .stud SI2 on the headstock in a clockwise direction into thefposition illustrated in Fig. 3, thus shifting the.

lever 3| I out of the path of a projection 3|3 on the bell crank lever 254, which renders the headstock operative; In this position of the parts, the headstock clutch 255 may then, be automatically engaged to start the rotation of the headstock and the crankshaft 2i to be lapped.

The lapping operation continues untilan electric time delay relay automatically disengages the headstock clutch after a predetermined time interval and again stops the rotation thereof, after which the cycle of operation of the valve and its interlocking plungers is again repeated.

After. the headstock has been stopped by shifting of the clutch, the bell crank lever 35d rocks in a clockwise direction (Fig. 10) and when the hydraulic motor 239 is actuated to rotate the shaft 22| and the disk 286 to clamp all of the lapping arms in an indexed position, the Bowden wire or exible cable 3l@ is pulled to rock the lever 3H in a counterclockwise direction, that is, downwardly, as shown in Fig. 3, until a portion of the lever 35i lies in the path of the end @t3 of the bell crank lever 255 so as to prevent starting the headstock rotation when the lapping arms are in a clamped position. It will-thus he seen that by providing a plurality of stop plungers to cause a restricted intermittent movement of the valve stern |04`both on its rearward and forward movements, all of the various mechanisms of the machine are interlocked so that they must all be -actuated in a denite and predetermined sequence.

When the valve |03 is in in Fig'. 3, -uid under pressure entering through l the pipe |02 enters a valve' chamber IM between the valve pistons I I I and I I2 and may pass through the pipes H5, and 304 to the various mechanisms'of the machine, In this position of the `valve, iluid may exhaust from the other side of the various iiuid'cylinders through the pipes ||8,

1 and 1'0) turn the exhaust ud to the reservoir |0| Electrical interlock v In order` to attain one object' of 'the invention, it is desirable to provide an electrical interlock between the main control valve, the.headstock clutch operating mechanism, the lapping arm clamping mechanism, and the footstock center.

'It is also desirable to 'provldean electrical time;

delay relay connected within said electrlcalrcircult whereby the lapping operation may proceed for a predetermined time interval, after which`- the Aheadstock clutch may be automatically disengaged and the main control valve |23 automatically shifted to move the various mechanisms oi' the machine to an inoperative or load- 'ing position.

The headstock clutch 256 is arranged to be actuated by means ofI a rock shaft 255 (Figs. 3 A rock arm 3|5 is' flxedly mounted on one 'end of the rock shaft 255. An electrical solenoid IIB is connected by a link 3|'l with the upper end of the rock arm 3|5 (Fig. 3) and serves to rock the shaft 255 in a clockwise direction (Flg.`3) to engage the headstock clutch 255 at the start of a lapping operation.

V: A solenoid Sie is connected by a link 3|@ to the lower end of the rock arm 3 i 5 and serves when energized to rock the arm sie and theshait 255 in a counterclockwise direction (Fig. 3) to disengage 'the headstock clutch 25d to vstop the lapping operation.

A switch 338 is xedly mounted on themachine I bese and is actuated by an arm 322 iixedly mounted relative to the valve rotor and the lever 'the position illustrated |56 and 305,-into the valve chamber Il! located between the valve pistons ||2and I I3, andrpass outv through the exhaust pipe |20 to the reservoir |0| Similarly, when the valve is shifted into its other extreme position (Fig. 6), uid Aunder pressure passing A through the pipe |02 enters the valve chamber i-lllocated between, thepistons` and ||'2 and may pass outthrongh pipes I IB, |56 and'305. At thelsame time, iinid may Vexhaust throughthe-pipes IIS, |55 and V304, through a im valvechamber 320, and outthrough anexhaust 926. The switch tti is connected in series with a'normally open switch 323 which is supported oni the upper-part of the lapping machine frame andis arranged to bev actuated by means of an arm 326 which is xedly moimted on the clamping mechanism shaft 2M.' The switch @23, as shown f in Fig. 3, is in a closed position, that is, when the ipping' arms are in an unclamped msition.

oi a lapping operation,l the lever 32% swings in a clockwise direction (Fig. 3) and the switch 323 automatically opens.

Connected in series with the switches 33| and en the lapping arms are clamped at the end 323 is a normally open switch are which is.

mounted. on the upper surface of the footstock 23. 'I'he switch 325 is arranged to be actuated by a bell crank lever 320 which in turn is rocked by means of a. cam 321. carried by the footstock center 5|. I y

'Ihe solenoid 3|6 is connected in series with the `switches 433|,7323 and 525 so that when *he lapping' machine is set in motion, the electrical interlock above disclosed isarranged so' that the headstock clutch cannot b e. engaged until the work center has moved. to an operative position and the clamping mechanism has been actuated to release the lapping arm. When the solenoid 3|6 isenergized, the rock arm 3|5 is rocked in a clockwise direction (Fig. 3) to shift theheadstock clutch 256 into engagement to rotate the headstock and thereby to effect a lapping operation. An electrical time delay relay 335, shown dagrammatically in Fig. 3, may be any voi' the standard commercial time relays which are in common use in the machine tool field. As illustrated in iFig. 3, a relay known commercially as the Microflex instantaneous reset timer manufactured by the Eagle. Signal Corporation under UnitedStates Patent No. 1,794,762 may be employed.

(Fig. 3) into operative engagement to support a lwork piece in the machine, the switch 325. is

closed. Similarly, when the clamping mechanism shaft 22| is rotated in a counterclockwise direction (Fig. 3) to unclamp the lapping arms for a lapping operation, the switch 323 is closed. These switches serve to complete the circuitI from the' power lines 336 to energize the solenoid 3|6 and thereby to shift the headstock.clutch into engagement to rotate the 4work piece and thereby initiate a lapping operation. l The lapping operation continues for a predetermined time interval energize the solenoid 3|8 to rock the arm 3|5 and as governed by. the adjustable time delay relay 335,. Shortly after the lapping operation starts, a contact within the time delay relay 335 is broken, thereby deenergizing the solenoid-3m.

'I'he lapping operation proceeds for a definite and predetermined time interval, after which a contact within the time delay relay 3,35 is made to the shaft 255 in a counterclockwise direction (Fig. 3) to disengage the headstock clutch 256 and thereby stop the rotation of the work piece being lapped. The time delay relay continues to function and after a'L slight interval of time has elapsed, a solenoid 330 is energized to cause a downward movement of the solenoid armature 329 to .movethe arrow-headed plunger 328 downwardly, thus permitting the released tension of the spring |3| to shift the control lever |24 and the valve |23 in a clockwise direction (Fig. 3) so that the control lever assumes the position |24a illustrated'in broken lines in Fig. 3.

Aswitch 340is actuated by-movement of the rock arm 3|5. Incase the solenoid 3| 8 .fails to function before the circuit is closed to energize the solenoid 330, the automatic shifting of the valve |23, -through the arm 322, shifts the switch 33|, closing the upper contacts therein. These contacts are connected in series with the switch 340" and the solenoid 3|8 so that current is again passed to energize the solenoid 3|8 to-disengage the headstock clutch. The valve |03 cannot be shifted toward the right '(Fig. 3) until the headstock clutch is disengaged and the stop 250 withdrawn. It will be readily apparent from the foregoing disclosure that an electrical interlock and timing device is provided whereby the lduration of the lapping operation may be accurately.con

trolled and-the main control valve, the clampingr mechanism, the footstock, and the headstock clutch interlocked electrically so that the lapping operation cannot be started until the other mechanisms of the machine have completed'their operative movement.

The operation of this' improved machine will be readily apparent from the foregoing disclosure. A work piece, such as a camshaft or a crankshaft 24, to be .lapped is laid in posit/ion on a work supporting cradle 345 which is supported on the table 2| between the head stock 22 and footstock 23, and the iiange of the crankshaft is positioned with the aligning hole in engagement with a driving pin onthe headstock. In this position of snoepen a' the machine, the valve stem |04 is in its rearward position, thatl is, vits right-hand .end position (Fig. 3), and the control lever |24 is in the broken line position |2411. The control lever |24 is then moved in a counterclockwise direction to shift the valve |23 so as to admit uid under pressure through the pipe |26 into the chamber |21 to cause thevalve stem |04 and the valve piston formed integrally therewith to move toward the left (Fig. 3) ,which movement operates first to admit iiuid under pressure through the pipe ||5 and pipe 12 to move the footstock center 5| into supporting engagement with the end of the work piece.` This movement Aserves also to close the switch 325. At the same time, fluid passing through the pipe ||5 enters the cylinder.,

chamber ||6 to cause a downward movement of the piston 66 (Fig. 2) to move the toggle levers 94 and 95 from their dotted line position into the full line position (Fig. 2) to rock the arms 80 and the entire lapping arm assembly into an operating position, which movement withdraws the stop plunger 280 and permits a further forward l movement ofthe valve stem |04.

The pressure being applied within the chamber |21, as soon' as the stop plunger 280 is withdrawn the valve stem" |04 moves automatically to its next position and fluid under pressure is admitted through the pipe |55 to the manifold or pipe |53 which conveys fluid to -all of the lapping arm cylinders to actuate the toggle levers on each arm and thereby swing the lap supporting arms or jaws into an operating position to hold the lapping element, namely the continuous strips of abrasive paper or cloth, in lapping engagement with all of the crankpins and bearings of' the shaft. This movement serves through the Bow` den wire or cable 213 to rock the bell crank 302 in a counterclockwise direction to withdraw the stop plunger 300, thus permitting a further movement of the valve stem |04 toward the left (Fig. 3). The continued automatic movement of the valve serves to open a port and admit iiuid under pressure through the pipe 304 to the lapping arm clamping motor 230-which rotates the shaft'22l and the disk 266 to unclamp the lapping arms. Rotation of the disk 266 in a counterclockwise direction (Fig. 3) serves through the Bowden wire or.v exible cable 3|0 tol rock the lever 3|| in a counterclockwise direction so that it is out of the path of the projection 3|3 ofv the bell crank lever 254, which renders the headstock mechanism operative. At the same time, the rotation of the shaft 22| serves through the lever 324 to close the switch 323, thus completing a circuit to energize the solenoid 3|6 which ation, the stop plunger 250 is in an operative.

position so as to prevent accidental shifting of the valve stem |04 toward the `right (Fig. 3). When the headstock is automatically stopped by the time delay relay, the -bell crank 254 (Fig. 3)

is rocked in a clockwise direction which serves` torock the bell crank lever 252 in a counterclocksnoepen A 1 -Y Z9 wise direction and thus withdraw the stop plunger 250 so that the valve stem |04 may be moved toward Athe rear or toward the right (F'ig. 3). After the headstock clutch has been disengaged, another contacter within the electrical time delay relay is madeto energize the solenoid 330 and thereby withdraw the plunger 328 so that the released tension of the spring |3| will rock the control leverl |24 in a clockwise direction into the broken line position |24a, thus reversing the position of the main control valve so as to .admit fluid under pressure through the pipe |29 into the valve chamber |28 to start the movement of the valve stem |04 toward the right (Fig. .3).1'

i This movement of the valve stem |04 continues until the stop collar 248 engages the stopplung er 280. Y

During this movement the valve shifts so as to admit uid under pressure through the pipe 3 305 to the lapping arm clamping motor 230 to rotate the shaft 22| in a clockwise direction (Fig. 3). to clamp all of the lapping arms in an indexed position. This movement serves to pull the Bowden wire SII to cause a counterclockwise 5 movement of the .lever 3|| to swing downwardly into the path of `the projection 3|3 of the bell crank 254 and thus lock the headstock so as to prevent startmg the work rotation while all of the lapping arms are clamped in an indexed pou sition. At the .same time the clampingl mechanism is being operated,'the lever 324 rocks in a clockwise direction, thus permitting the switch 323 to open, thereby opening the circuit so as a to render the solenoid 3|! inoperative.

5 At the same time, the rotation ofthe disk 266!- in a clockwise direction pulls theBowden wire or cable 2l! to move the b ellcrank'262 in a 1 coimterclockwise direction and thereby withdraw the stop plunger'28l, thus permitting the valve g stem |04 to be automatically moved by uid under pressure toward the rear or right, as shown in Fig. 3. The valve stem'lll may then be moved until the stop collar 24B engages the stop plunger 210 which serves to open a port so as L5 to admit fluid under pressurenthrough the pipe |58 into the manifold or pipe |54 which causes a downward movement of all of the pistons within the lapping arm cylinders to actuate all of the toggle levers and to open the lap supporting i members or jaws.

lap supporting members or jaws, the cable 2131s pulled to rock the bell crank lever 212 in a clockwise direction (Fig. 3) to withdraw the stop Vplunger 210, thus' permitting the, valve stem |04 55 to be automatically moved byilulcl` under pressure into its extreme rearward or right-hand position. This movementof the valve iserves Ato open the port so as to admit fluid under pressure through the pipe 15 into cylinder chamber 50.14 to withdraw the footstock center |V and to admit fluid under pressure through the pipe H8 into the cylinder chamber ||1 o f the cylinder 84 to cause the arms 80 to swing the entire lapping arm assembly to an inoperative position,

85 afteri which the lapped crankshaft may be' ,re-'- moved from the machine.

A latch l is provided to facilitate holding the control lever |24 in a central 'or neutral position |241) (Fig. V1). In this position of the lever,

70 the valve |23 is positioned to allow by-passing.

During the opening of the vention set forth in the cpending U; S. application Serial No. 233,003 led October 3, 1938.

It will thus be seen that there has been provided by this invention apparatus in whichthe various objects hereinabove set forth together 5 with. many thoroughly'practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodimentabove set forth, it is to be understood that 10 all matter hereinbefore set forth or shown'in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

' I claim: u

1. A lapping machine having a plurality of lapping arms, a rotatable work support including a headstock and a foot'stock, a carrier to support said arms which is movable to and from an' operative position, a fluid motor for actuating each of said members, a control valve to control the iiow of fluid under pressure to all ofnsaid fluid motors, and a pilot valve to'shift said control valve to start the lapping cycle. 1 A

2. A lapping machine having a plurality of lapping arms, a rotatable work support including a headstock and a footstock, a carrier to support said arms which is movable to andfrom-an operative position, a uid motor for actuating each of said members, a control valve therefor, a plurality of stops to interrupt the movement of said valve, connections between each of said stops and y one of Saidelements, and a manually operable pilot valve to shift said control valve to startwthe lapping cycle and to maintain a pressure on said control valve Aso that it isV automatically' and 35 rality of lapping arms, a carrier to support-said 40 1 arms which is movable to and from an operative position, a lapping arm clamping mechanism to clamp said arms in an indexed position relative 'to said carrier, a rotatable work support including a headstock and a footstock, a separate 45.

uid motor for actuating each of said members. a control valve therefo means including an electrically operated clutch to startand stop said.

headstock, an electrical interlock including a valve actuated switch, a footstock actuated switch, and a clamping mechanism actuated switch, each of said switches being connected m ser-ies with said electrically operated clutch mechanism to prevent starting said headstock until the footstock is in supporting engagement with said 55 work piece andthe clamping mechanism has un- Y clamped the lapping arms. 1 .i 4. A lapping machine having aplurality of lapping arms, 1a rotatable work support includ- 1 ing a headstock and a footstock, a carrier tosup- 6o port said 'arms which is-mov'able to andfrom an operativeV position, `a fluid motor for actuating.

veach of said members, a control valve therefor, -a pilot valve to shift said control valve toY start the lapping cycle, an electrical interlockincluding 3s an electricaly operated headstock clutch.' a footstock actuated switch, and electrical' connections Y therebetween to prevent 'actuation of said clutchl to start the work rotation until' the headstock is in supporting engagement with a work piece. Y Y 7n 5. A lapping mchine. having aplurallty of lapping arms, 1a rotatable work;v support including a headstock and afoot'stock, a carrierrto support said arms which-ls movable ltol and from 'an operative position-a lapping mech- 35 vlsaidclutch to'stai't the tvork rotation until the '-headstoclrisin supporting engagement with a workpiece.'-

i 6.Alapping machine having a plurality of lapipin'g arms, a rotatable'worlr support yincluding a heads'tockanda ioots'tock,. a carrier tosupport said arms which is movable to and irom an operative position', a lapping arm clamping mechfanism; a A:duid motor for actuating each o'i-sald mernbers; a-control valve therefor, a pilot valve to .shiftsaidcontrol valve'to start the lapping cycle,

.-anelectrical interlock including a solenoid actuated -headstoclr ehrlich,rv aiootstocl: actuated switch, a clamping mechanism' actuated switch, and a control valveI actuated switch, said switches being interconnected with said solenoid so as to prevent engagement oi said clutch until each oi said switches has been actuated.

7. In a lapping machine having a plurality of lapping arms, a rotatable worlr support including a headstock and a footstoclr, a carrier to support said arms which is movable to and from an operative position, a lapping arm clamping mechanism, a duid motor for,I actuating. each of-said members, a control valve to control the admission of nuid under pressure to all of said motors, a main control valveA to admit fluid under pressure to either end ci said control valve,l a plurality of stops intermittently to interrupt the prom gressive movement of said control valve, connec.

tions between each of said-stops and one of said elementsv automatically to withdraw said stop after 'the element has functioned, and automatically actuated meansto shift said control valve to start a lapping cycle automatically to move said valve intermittently as successive stops are with a drawn.

arcanes t. Inca lapping machineirlr :a plurality'ol' lapping arms, a rotatable work support including a headstocl: and a footstock, a carrier to support said arms which is movable to and from an oper:- ative position, a lapping arm clamping mechamsm, a iiuid motor for 'actuating each of -sald members, a control valve to control the admissionI oi fluid under pressure to all of said motors,'a main control valve to admit Huid underpressure to either end oi said controlvalve, a plurality of stops intermittently to interrupt the progressivemovement oi said control valve, connections between each of said stops and one oit said elements f automatically to withdraw said stop after the element has functioned, automatically actuated means to shirt said control valvetorstart a lapping cycle automaticallyV to move said valve in:

termittently as successive stops-are'withdrawn. an Ielectrical time delay relay, and anv automatif cally actuated mechanism to shift said mainv con- A trol valve into a reverse position to stop the lap# ping cycle aiter the lapping Voperation has continued for a predetermined time interval as governed by said time delay relay.

9. A lapping machine having a plurality of lapping arms, a rotatable worlr support including a headstock and a iootstock, a carrier to support said arms rvhlcl'iY is movable to and from an operative position, a' nuld motor for actuating each of said members, a control valve therefor, a pilot valve to shirt said control valve to start the lapping cycle, an electrically operated headstock clutch, a valve actuated switch, `and an electrical time delay relay rendered operative by actuation oi" said valve actuated switch to actuate said electrically operated headstock clutch to' initiate a lapping operation, said time delay relay being so constructed and connected as to actuate said electrically operated headstock clutch after the lappingoperation has proceeded for apredetermined L time interval'to'stop rotation ofsaid headstock and work piece.

. WALLACE H. WOOD. 

